1. Field of Invention
The disclosure relates to wireless communications, and more specifically to a wireless communication device capable of accurately estimating its position while within a limited wireless communication environment, and corresponding method.
2. Related Art
Wireless communication devices, such as cellular telephones to provide an example, are becoming commonplace in both personal and commercial settings. The wireless communication devices provide users with access to all kinds of information, as well as the ability to communicate with other such devices across large distances. For example, a user can access the internet through an internet browser on the device, download miniature applications (e.g., “apps”) from a digital marketplace, send and receive emails, or make telephone calls using a voice over internet protocol (VoIP). Consequently, wireless communication devices provide users with significant mobility, while allowing them to remain “connected” to communication channels and information.
Wireless communication devices communicate with one or more other wireless communication devices or wireless access points to send and receive data. Typically, a first wireless communication device generates and transmits a radio frequency signal modulated with encoded information. This radio frequency signal is transmitted into a wireless environment and is received by a second wireless communication device. The second wireless communication device demodulates and decodes the received signal to obtain the information. The second wireless communication device may then respond in a similar manner. The wireless communication devices can communicate with each other or with access points using any well-known modulation scheme, including: amplitude modulation (AM), frequency modulation (FM), quadrature amplitude modulation (QAM), phase shift keying (PSK), quadrature phase shift keying (QPSK), and/or orthogonal frequency-division multiplexing (OFDM), as well as any other communication scheme that is now, or will be, known.
Modern wireless communications devices use any of varying methods to obtain their location. By obtaining its location, the wireless communication device can perform location-specific functions and/or operate location-specific applications. In an outdoor environment, the wireless communication device can easily obtain its location through the use of GNSS satellite information. Similarly, triangulation can be easily performed with nearby base stations because those base stations consistently transmit signals at set power levels.
However, in an indoor environment, the device may not have access to GNSS and/or nearby base stations sufficient to make an accurate location determination. Further, although many indoor environments include other communication access points, such as Bluetooth and WiFi, these communication protocols employ fluctuating transmission powers and sleep/hibernate modes. As such, performing conventional location and mapping techniques in an indoor environment will fail to produce accurate results.